The results of the first completed 'phase 0' trial in cancer therapy were announced. The phase 0 trial is the earliest clinical trial type in the US, designed to give preliminary data about the action and bioavailability of candidate medicines. The 2009 phase 0 trial in oncology came from Abbott Laboratories, which was exploring the potential of a poly–ADP-ribose polymerase inhibitor.

Cervarix received approval from the US Food and Drug Administration. This vaccine, from GlaxoSmithKline, blocks infection by certain strains of the human papillomavirus and thereby prevents against cervical cancer. The approval received little fanfare compared with that of Merck's Gardasil.

Mouse studies suggested new consequences of high-fat diets in moms-to-be. In research presented at the annual meeting of the Society for Neuroscience, scientists reported that mouse pups born to mothers fed a high-fat diet during pregnancy showed a greater affinity for drinking a sugar solution than their control counterparts. The finding comes at a time when type 2 diabetes is increasingly common, including among teens.

A retrovirus was found to be common in aggressive prostate cancers. An analysis of prostate cancer samples found that the presence of the Xenotropic murine leukemia virus–related virus (XMRV)—a common retrovirus—was associated with more aggressive tumors. In a study published shortly afterward, another team of scientists reported a possible link between XMRV and chronic fatigue syndrome.